fix(ui): [UI7-2] 统一全局 Design Tokens，移除冗余字体，修复异常色值引用

client/src/pages/WorkflowTasksPage.tsx

@@ -78,7 +78,7 @@ export function WorkflowTasksPage() {
         ) : null}
 
         {!query.isLoading && !query.isError ? (
-          <div className="rounded-lg border border-slate-200">
+          <div className="rounded-lg border border-zinc-200">
             <Table data-testid="workflow-tasks-table">
               <TableHeader>
                 <tr>
@@ -94,8 +94,8 @@ export function WorkflowTasksPage() {
                   query.data?.items.map((task) => (
                     <TableRow data-testid="workflow-task-row" key={task.id}>
                       <TableCell>
-                        <div className="font-medium text-slate-900">{task.stepName}</div>
-                        <div className="text-xs text-slate-500">{task.id}</div>
+                        <div className="font-medium text-zinc-900">{task.stepName}</div>
+                        <div className="text-xs text-zinc-500">{task.id}</div>
                       </TableCell>
                       <TableCell className="font-mono text-xs">
                         {task.workflowInstance?.entityId}
@@ -116,7 +116,7 @@ export function WorkflowTasksPage() {
                   ))
                 ) : (
                   <TableRow>
-                    <TableCell className="py-3 text-slate-500" colSpan={5}>
+                    <TableCell className="py-3 text-zinc-500" colSpan={5}>
                       暂无数据
                     </TableCell>
                   </TableRow>